Releasable threaded connection for modular implants

ABSTRACT

An orthopaedic prosthesis assembly includes a first prosthetic component, a second prosthetic component, and a fastener. The first prosthetic component includes a threaded bore. The second prosthetic component includes an opening and a threaded inner wall that extends inwardly from the opening. The fastener includes a first axial section having a first plurality of threads engaged with the threaded inner wall the second prosthetic component, and a second axial section having a second plurality of threads engaged with the threaded bore of the first prosthetic component to secure the first prosthetic component to the second prosthetic component.

This application is a divisional of and claims priority under 35 U.S.C.§ 121 to U.S. patent application Ser. No. 15/890,516, now U.S. Pat. No.10,201,430, filed Feb. 7, 2018, which is a divisional of U.S. patentapplication Ser. No. 15/005,629, now U.S. Pat. No. 9,895,232, filed onJan. 25, 2016, each of which is hereby incorporated by reference.

TECHNICAL FIELD

The present disclosure relates generally to an implantable orthopaedicprosthesis, and more particularly to an implantable knee prosthesis.

BACKGROUND

During the lifetime of a patient, it may be necessary to perform a jointreplacement procedure on the patient as a result of, for example,disease or trauma. The joint replacement procedure may involve the useof a primary prosthesis which is implanted into one or more of thepatient's bones. In the case of a knee replacement procedure, a tibialtray is implanted into the patient's tibia. A bearing is secured to thetibial tray. The condyle surfaces of a replacement femoral componentbear against the tibial bearing.

Such a primary knee prosthesis may also include a number of elongatedintramedullary stem components and optional prosthetic components (e.g.,sleeves and/or adaptors) which are implanted in the patient's tibiaand/or femur. To secure a stem component and/or other components to thepatient's tibia and/or femur, the intramedullary canal of the patient'stibia and/or femur is first surgically prepared (e.g., reamed) such thatthe stem component and/or other components may be subsequently implantedtherein. In some designs, the stem component is implanted in thepatient's bone by use of cementless fixation. One type of such a designis known as a ‘press fit’ stem component.

On occasion, the primary knee prostheses fails. Failure can result frommany causes, including wear, aseptic loosening, osteolysis, ligamentousinstability, arthrofibrosis and patellofemoral complications. When thefailure is debilitating, revision knee surgery may be necessary. In arevision, the primary knee prosthesis is removed and replaced withcomponents of a revision prosthetic knee system.

Various orthopaedic surgical instruments are used throughout such anorthopaedic procedure. For example, bone saws and/or reamers may be useto surgically prepare a bone surface to accept an orthopaedic implant.Additionally, depending on the particularly implant, a variety oforthopaedic surgical instruments may be used to assembly, disassembly,and/or install the orthopaedic implant into the prepared bone.

SUMMARY

According to one aspect of the disclosure, an orthopaedic surgicalinstrument is disclosed. The orthopaedic surgical instrument includes afirst prosthetic component, a second prosthetic component, and afastener. The first prosthetic component includes a first end, a secondend opposite the first end, and a threaded bore defined in the firstend. The second prosthetic component includes an outer surface, an innersurface positioned opposite the outer surface that is configured to facea bone of a patient, and a post extending from the inner surface along alongitudinal axis, the post including an opening defined in a free endand a threaded inner wall that extends inwardly from the opening todefine a lower passageway in the post. The fastener includes a firstaxial section having a first plurality of threads engaged with thethreaded inner wall the second prosthetic component, and a second axialsection having a second plurality of threads engaged with the threadedbore of the first prosthetic component to secure the first prostheticcomponent to the first prosthetic component.

In some embodiments, the first plurality of threads and the secondplurality of threads twist in opposite directions.

In some embodiments, the first plurality of threads are one ofright-handed threads and left-handed threads and the second plurality ofthreads are the other of right-handed threads and left-handed threads.

In some embodiments, the first plurality of threads twist in a samedirection as the second plurality of threads.

In some embodiments, the first plurality of threads and the secondplurality of threads are one of right-handed threads and left-handedthreads.

In some embodiments, the first plurality of threads has a first threadpitch and a first lead and the second plurality of threads has a secondthread pitch that is same as the first thread pitch and a second leadthat is the same as the first thread pitch.

In some embodiments, the outer surface of the second prostheticcomponent has an opening defined therein, and an upper passagewayconnects the opening to the lower passageway.

In some embodiments, the orthopaedic prosthesis system further includesa tool having an end sized to be received in the upper passageway and isconfigured to engage the head of the fastener to selectively rotate thefastener and decouple the first prosthetic component from the secondprosthetic component.

In some embodiments, the rotation of the fastener in a first directioncauses the fastener to move axially away from the second prostheticcomponent within the upper passageway of the component.

In some embodiments, the first prosthetic component is a stem componenthaving an elongated body extending from the first end, and the secondprosthetic component is a femoral component having a pair of condylesurfaces.

In some embodiments, the first prosthetic component is a stem componenthaving an elongated body extending from the first end, and the secondprosthetic component is a tibial component comprising a tibial trayhaving a platform and the post extends from the platform.

According to another aspect of the disclosure, a method for joint lineassembly of an orthopaedic prosthesis assembly is disclosed. The methodincludes threading a first axial section of a fastener into a threadedbore defined in a first prosthetic component by rotating the fastener ina first direction, and threading a second axial section of the fastenerinto a threaded lower passageway defined in a second prostheticcomponent by rotating the first prosthetic component in a seconddirection to secure the first prosthetic component to the secondprosthetic component.

In some embodiments, the method further includes advancing a toolthrough an upper passageway defined in the second prosthetic componentto engage an end of the tool to the second axial section of thefastener, and rotating the tool in the second direction with the end ofthe tool engaged with the fastener to move the first axial section ofthe fastener out of engagement with the first prosthetic component.

In some embodiments, the first axial section includes a first pluralityof threads having a first thread pitch and the second axial sectionincludes a second plurality of threads having a second thread pitch thatmatches the first thread pitch.

In some embodiments, the second axial section has a diameter greaterthan a diameter of the first axial section of the fastener.

According to another aspect of the disclosure, another method includesengaging a first axial section of a fastener with a threaded boredefined in a first prosthetic component, engaging a second axial sectionof the fastener into a threaded lower passageway defined in a secondprosthetic component, and rotating the fastener in a first direction tosimultaneously move the first axial section and the second axial sectioninto the first prosthetic component and the second prosthetic component,respectively.

In some embodiments, the method further includes advancing a toolthrough an upper passageway defined in the second prosthetic componentextending away from the lower passageway, engaging an end of the tool tothe second axial section of the fastener, and rotating the tool in asecond direction to simultaneously move the first axial section and thesecond axial section out of engagement with the first prostheticcomponent and the second prosthetic component, respectively.

In some embodiments, the first axial section has a same diameter as adiameter of the second axial section.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description particularly refers to the following figures,in which:

FIG. 1 is a perspective view of an implantable orthopaedic kneeprosthesis assembly;

FIG. 2 is an exploded, partial cross-section perspective view of atibial tray component and a fastener of the implantable orthopaedic kneeprosthesis assembly of FIG. 1;

FIG. 3 is an exploded, partial cross-section perspective view of afemoral component and the fastener of the implantable orthopaedic kneeprosthesis assembly of FIG. 1;

FIGS. 4-5 are cross sectional elevation views showing the fastener beingattached to the stem component of FIG. 1;

FIGS. 6-7 are cross sectional elevation views showing a procedure forattaching a prosthetic component to the stem component and fastener toform a component assembly;

FIGS. 8-10 are cross sectional elevation views showing a surgical toolbeing used to remove the fastener from the stem component to disassemblethe component assembly of FIGS. 6-7;

FIGS. 11-12 are cross sectional elevation views showing anotherembodiment of the fastener being used to attach a prosthetic componentto the stem component to form an component assembly; and

FIGS. 13-14 are cross sectional elevation views showing a procedure fordisassembling the component assembly of FIGS. 11-12.

DETAILED DESCRIPTION OF THE DRAWINGS

While the concepts of the present disclosure are susceptible to variousmodifications and alternative forms, specific exemplary embodimentsthereof have been shown by way of example in the drawings and willherein be described in detail. It should be understood, however, thatthere is no intent to limit the concepts of the present disclosure tothe particular forms disclosed, but on the contrary, the intention is tocover all modifications, equivalents, and alternatives falling withinthe spirit and scope of the invention.

Terms representing anatomical references, such as anterior, posterior,medial, lateral, superior, inferior, etcetera, may be used throughoutthis disclosure in reference to both the orthopaedic implants describedherein and a patient's natural anatomy. Such terms have well-understoodmeanings in both the study of anatomy and the field of orthopaedics. Useof such anatomical reference terms in the specification and claims isintended to be consistent with their well-understood meanings unlessnoted otherwise.

Referring to FIG. 1, an implantable orthopaedic knee prosthesis assembly10 for use in the performance of an orthopaedic knee replacementprocedure is shown. The knee prosthesis assembly 10 includes a femoralcomponent 12, a tibial tray component 14, and a bearing 16. The kneeprosthesis assembly 10 also includes a stem component 18 secured to thefemoral component 12 and a stem component 18 secured to the tibial traycomponent 14. As will be described in detail below, each of thecomponents 12, 14 is secured to the stem component 18 via a fastenersuch that the selected component 12, 14 may be disassembled and removedseparately from the stem component 18 while the components 12, 14, 18are positioned in the patient's bone.

The tibial tray component 14 is configured to be implanted into asurgically-prepared proximal end of a patient's tibia (not shown). Thetibial tray component 14 includes a platform 20 having an elongated stemmounting post 22 extending inferiorly away from its inferior surface 24.The mounting post 22 is configured to engage the stem component 18, aswill be described in more detail below.

The bearing 16 is securable to the tibial tray component 14. Inparticular, the bearing 16 may be snap-fitted into the tibial traycomponent 14 such that the bearing 16 is fixed relative to the tibialtray component 14 (i.e., it is not rotatable or moveable in theanterior/posterior or medial/lateral directions). In other embodiments,the bearing 16 may be secured in a manner that allows it to rotaterelative to the tibial tray component 14. The bearing 16 includes alateral bearing surface 26 and a medial bearing surface 28. The bearingsurfaces 26, 28 are configured to articulate with a lateral condylesurface 30 and a medial condyle surface 32, respectively, of the femoralcomponent 12. Specifically, the femoral component 12 is configured to beimplanted into a surgically-prepared distal end of a patient's femur,and is configured to emulate the configuration of the patient's naturalfemoral condyles. As such, the lateral condyle surface 30 and the medialcondyle surface 32 are configured (e.g., curved) in a manner whichmimics the condyles of the natural femur. The lateral condyle surface 30and the medial condyle surface 32 are spaced apart from one anotherthereby defining an intercondylar notch 34 therebetween.

The condyle surfaces 30, 32 are formed in a bearing surface 36 of thefemoral component 12. The femoral component 12 also includes anelongated stem mounting post 22, extending superiorly away from itsopposite backside surface 40, which is configured to engage the stemcomponent 18, as will be described in more detail below. The stemcomponent 18 and the femoral component 12 may be implanted into asurgically-prepared (e.g., reamed or broached) patient's femur (notshown).

As shown in FIG. 1, each of the stem components 18 includes anelongated, generally cylindrical stem body 42. The elongated stem body42 further includes a threaded bore 120 defined at an end 44 thereof(see FIGS. 3-13). When the stem component 18 is secured to the tibialtray component 14, the end 44 is the proximal end of the elongated stembody 42, which extends distally away from the post 22 of the traycomponent 14 and terminates at rounded distal end 46 that defines theinferior-most surface of the stem component 18. When the stem component18 is secured to the femoral component 12, the end 44 is the distal endof the elongated stem body 42, which extends proximally away from themounting post 22 of the femoral component 12 and terminates at roundedproximal end 52 that defines the superior-most surface of the stemcomponent 18.

The stem component 18 may be provided in a number of differentconfigurations in order to fit the needs of a given patient's anatomy.In particular, the stem component 18 may be configured in variousdifferent lengths to conform to the patient's anatomy (e.g., arelatively long stem component 18 for use with a long femur or tibia, arelatively short stem component 18 for use with a short femur or tibia,etcetera). The stem component 18 may also be provided in varying bodydiameters to fit the needs of a given patient's anatomy. The bodydiameter of a given stem component 18 is the stem component'smedial/lateral cross sectional width in the cylindrical midsection ofthe stem component's body (i.e., not at its tapered post or its distaltip). In other embodiments, the stem component 18 may have some othershape (e.g., non-cylindrical) and size. Likewise, the femoral component12 and the tibial tray component 14 may be provided in various differentsizes to fit the needs of a given patient's anatomy.

The knee prosthesis assembly 10 may also include a number of optionalcomponents in various embodiments. For example, the knee prosthesisassembly 10 may include a femoral sleeve component 48. The femoralsleeve component 48 may be used to facilitate implantation of thefemoral component 12 in the presence of reduced bone quality in thepatient's femur. The femoral sleeve component 48 is configured to besecured to the femoral component 12 so as to be positioned between thefemoral component 12 and the stem component 18.

Referring now to FIG. 2, the tibial tray component 14 is shown with afastener 56 that is configured to attach the tibial tray component 14 tothe stem component 18. As described above, the tibial tray component 14includes the platform 20 having the mounting post 22 extendinginferiorly away from the inferior surface 24 of the platform 20 to anouter end 58. The mounting post 22 further includes an outer opening 60defined in the outer end 58 and an inner wall 62 that extends inwardlyfrom the outer opening 60 along the longitudinal axis 64 to a proximalopening 66 defined the platform 20 of the tibial tray component 14. Theinner wall 62 of the tibial tray component 14 defines a first passageway70 and a second passageway 72. A rim surface 74 of the inner wall 62 isdefined at the intersection of the first passageway 70 and the secondpassageway 72.

The first passageway 70 extends away from the proximal opening 66 of theplatform 20 to the rim surface 74 of the mounting post 22. The secondpassageway 72 extends inferiorly from the rim surface 74 to the outeropening 60 at the outer end 58 of the mounting post 22. The inner wall62 includes a plurality of internal threads 76 in the second passageway72 that are configured to receive corresponding threads of the fastener56. Further, the passageway 70 has a diameter 82 smaller than a diameter84 of the passageway 72 such that the rim surface 74 is defined betweenthe inner ends of the passageways 70, 72, as shown in FIG. 2. Thepassageway 72 is configured to receive the fastener 56 and thepassageway 70 is configured to receive a surgical instrument tool 150,as will be described in more detail below.

As shown in FIG. 2, the fastener 56 is embodied as a screw. It should beappreciated, however, that the fastener 56 may be any fastening deviceor component configured to extend through the tibial tray component 14to the stem component 18 to secure the tibial tray component 14 to thestem component 18. The fastener 56 includes an elongated shaft 92 havinga threaded first section 90 and a threaded second section 94 positionedopposite the first section 90. A substantially smooth unthreaded sectionconnects the sections 90, 94. It should be appreciated that in otherembodiments the entire shaft of the fastener may be threaded.

The threads of the section 90 twist in the same direction as the threadsof the section 94. Specifically, in the illustrative embodiment, thesection 94 has right-handed threads 98 and the section 90 hasright-handed threads 100. As a result, when the fastener 56 is rotatedin one direction, it is advanced in the same direction relative toeither the stem component 18 or the tibial tray component 14. Forexample, when the fastener 56 is rotated clockwise relative to the stemcomponent 18, it may be threaded into the threaded bore 120 of the stemcomponent 18, as shown in FIGS. 4-5. When the fastener 56 is rotatedcounterclockwise, as shown in FIGS. 6-7, it may be advanced out of thestem component 18 and into the tibial tray component 14. In theillustrative embodiment, the thread pitch and lead of the section 90matches the thread pitch and lead of the section 94 so that one rotationof the fastener 56 in either direction results in the same travelaxially for the sections 90, 94.

Further, the section 90 has a diameter 102 greater than a diameter 82 ofthe first passageway 70 of the tibial tray component 14 and a diameter104 of the fastener section 94. Accordingly, the section 90 of thefastener 56 may positioned in the second passageway 72 of the tibialtray component 14 but does not pass beyond the rim surface 74 into thefirst passageway 70. In some embodiments, the second passageway 72 mayinclude a relatively smooth upper section and a threaded lower section.In such embodiments, the fastener 56 may be threaded through thethreaded lower section of the lower passageway but does not advancebeyond the lower threaded section.

As shown in FIG. 2, the shaft 92 of the fastener 56 further includes atool socket 106 defined in an upper surface 108. The tool socket 106 isshaped to accept a surgical instrument tool 150, as will be described indetail below.

Referring now to FIG. 3, the femoral component 12 also includes amounting post 22 that extends superiorly away from its opposite backsidesurface 40. The mounting post 22 of the femoral component 12 alsoincludes an outer end 58 and an inner wall 62 that extends inwardly froman opening 60 along the longitudinal axis 114 to a distal opening 116defined in the intercondylar notch 34 of the femoral tray component 12.The inner wall 62 of the femoral tray component 12 defines a firstpassageway 70 and a second passageway 72 in the post 22. A rim surface74 of the inner wall 62 is defined at the intersection of the firstpassageway 70 and the second passageway 72.

The first passageway 70 extends away from the distal opening 116 to therim surface 74 of the mounting post 22 of the femoral component 12. Thesecond passageway 72 extends away from the rim surface 74 to the outeropening 60 at the outer end 58 of the mounting post 22. The inner wall62 includes a plurality of internal threads 76 in the second passageway72 that are configured to receive corresponding threads of the fastener56. Further, the passageway 70 has a diameter 82 smaller than a diameter84 of the passageway 72 such that the rim surface 74 is defined betweenthe inner ends of the passageways 70, 72, as shown in FIG. 3. Thepassageway 72 is configured to receive the fastener 56 and thepassageway 70 is configured to receive a surgical instrument tool 150

As described above, the fastener 56 includes an elongated shaft 92having a threaded first section 90 and a threaded second section 94positioned opposite the first section 90. Because the fastener section90 has a diameter 102 greater than a diameter 82 of the first passageway70 of the femoral component 12, the section 90 of the fastener 56 may bepositioned in the second passageway 72 of the femoral component 12 butdoes not pass beyond the rim surface 74 into the first passageway 70.

Referring now to FIGS. 4-7, a procedure for assembling a componentassembly 134 is shown. The component assembly 134 may include a selectedprosthetic component 136 such as, for example, a femoral component 12 ortibial tray component 14, and a stem component 18. To prepare thecomponent assembly 134, the surgeon may first align the elongated shaft92 of the fastener 56 to the threaded bore 120 of the stem component 18,as shown in FIG. 4. The surgeon may then rotate the fastener 56 in thedirection indicated by arrow 142 such that the threaded section 94 ofthe elongated fastener shaft 92 may advance axially into the threadedbore 120 of the stem component 18, thereby forming an intermediateassembly 144, as shown in FIG. 5. In the illustrative embodiment, thedirection of arrow 142 is clockwise because the threads 98 of thefastener section 94 are right-handed threads. In other embodiments, thethreads may twist in the opposite direction (i.e., may be left-handedthreads).

The intermediate assembly 144 may then be attached to the selectedprosthetic component 136 to form the component assembly 134 as shown inFIGS. 6-7. In the illustrative embodiment, the surgeon may thread thethreaded section 90 of the fastener 56 into the threaded passageway 72of the selected component 136 by rotating the entire intermediateassembly 144 counterclockwise, as indicated by arrow 146. For example,if the selected component 136 is a tibial tray component 14, the surgeonmay align the threaded section 90 of the fastener 56 with the passageway72 of the mounting post 22 of the tibial tray component 14. The surgeonmay then rotate the intermediate assembly 144 in the direction indicatedby arrow 146 (i.e., counterclockwise), which is opposite the firstdirection 142 (i.e., clockwise). As the threaded section 90 of thefastener 56 of the intermediate assembly 144 is rotated into the outeropening 60 of the mounting post 22, the external threads 100 of thethreaded section 90 are threaded superiorly into the internal threads 76of the passageway 72. The user may continue to rotate the intermediateassembly 144 to move the end 44 of the stem component 18 into contactwith the outer end 58 of the mounting post 22. When the stem component18 contacts the mounting post 22, the threaded section 90 is fullypositioned in the second passageway 72 of the mounting post 22, and theprosthetic component 136 (i.e., the tibial tray component 14 or femoralcomponent 12) is securely coupled to the stem component 18 via thefastener 56, thereby forming a component assembly 134, as shown in FIG.7. The assembly 134 may then be impacted in a surgically-preparedpatient's bone.

Referring now to FIGS. 8-10, should a revision surgery become necessary,the surgeon may disassemble the component assembly 134 to remove theassembly 134 from the patient's bone. To do so, the surgeon may removethe selected component independently from the stem component 18positioned in the patient's intramedullary canal. In the illustrativeembodiment, removing the selected component from the stem component 18involves unscrewing the fastener 56 from the stem component 18 to movethe threaded section 94 of the fastener 56 completely out of engagementwith the threaded bore 120 of the stem component 18. As describedpreviously, the threaded section 90 of the fastener 56 includes the toolsocket 106 that is shaped to accept a surgical instrument tool 150. Forexample, the tool socket 106 may be hex-shaped to accept a hex driver.The tool socket 106 may be otherwise shaped to accept a surgicalinstrument tool head 152 of a different shape.

For example, FIGS. 8-10 illustrate the disassembly process of thecomponent assembly 134 when the selected component 136 is the tibialtray component 14. To remove the tibial tray component 14 from the stemcomponent 18, the surgeon may advance the tool head 152 of the tool 150through the proximal opening 66 into the first passageway 70 of thecomponent 14 and into the tool socket 106 of the fastener 56. Thesurgeon may then rotate the surgical instrument tool 150 to move thethreaded section 94 of the fastener 56 out of engagement with thethreaded bore 120 of the stem component 18. When the tool head 152 isproperly inserted into the tool socket 106 of the fastener 56, thesurgeon may rotate the surgical instrument tool 150 about thelongitudinal axis 138 in the second direction 146 (i.e.,counterclockwise). As the tool 150 rotates the fastener 56 in the seconddirection 146, the threaded section 90 of the fastener 56 moves axiallyout of the stem component 18 and deeper into the passageway 72 of thetibial tray component 14.

As described previously, the section 94 of the fastener 56 has thediameter 104 smaller than the diameter 102 of the section 90 of thefastener 56. Accordingly, as the section 90 advances axially, thesection 94 also advances into the passageway 72 of the tibial traycomponent 14, as shown in FIG. 9, until the fastener 56 is completelydisengaged from the threads of the stem component 18, as shown in FIG.9. When the elongated shaft 92 is positioned fully in the lowerpassageway 72, the threaded section 94 of the fastener 56 does notengage the internal threads 76 of the second passageway 72 of the tibialtray component 14. The surgeon may then remove the tibial tray component14 from the patient's bone while the stem component 18 remains in theintramedullary canal. Subsequently, the stem component 18 may be removedfrom the intramedullary canal of the patient's tibia using anotherremoval tool. The surgeon may then assemble a revision componentassembly including another tibial tray component and stem component andmay implant the revision component assembly 134 back into theintramedullary canal of the patient's tibia.

Referring now to FIGS. 11-14, a component assembly 234 is shown withanother embodiment of a fastener (hereinafter fastener 256). Theembodiment of FIGS. 11-14 includes many of the same features describedabove in regard to FIGS. 1-10. The same reference numbers are used inFIGS. 11-14 to identify features that are the same or similar to thosedescribed above in regard to FIGS. 1-10. In the illustrative embodiment,the component assembly 234 may include a selected prosthetic component136 such as, for example, a femoral component 12 or tibial traycomponent 14, and a stem component 218. Similar to the stem component 18described above, the stem component 218 includes an elongated stem body42 that has a threaded bore 220 defined at an end 44 thereof. In theembodiment of FIGS. 11-14, the elongated body 42 has a plurality ofleft-handed threads 240 that define the bore 220.

As shown in FIG. 11, the fastener 256 is embodied as a screw. It shouldbe appreciated, however, that the fastener 256 may be any fasteningdevice or component configured to extend through the component 136 tothe stem component 218 to secure the component 136 (i.e., the tibialtray component 14 or the femoral component 12) to the stem component 18.The fastener 256 includes an elongated shaft 292 having a threaded firstsection 290 and a threaded second section 294 positioned opposite thefirst section 290. A substantially smooth unthreaded section connectsthe sections 290, 294. It should be appreciated that in otherembodiments the entire shaft of the fastener may be threaded.

The threads of the section 290 twist in one direction and the threads ofthe section 294 twist in the opposite direction. Specifically, in theillustrative embodiment, the section 294 has left-handed threads 298 andthe section 290 has right-handed threads 300. Accordingly, when thefastener 256 is rotated counterclockwise or clockwise, it is advanced inopposite directions relative to the stem component 218 and the component236.

For example, as shown in FIGS. 11-12, the fastener 256 may be alignedwith both the mounting post 22 of the component 136 and the threadedbore 220 of the stem component 218. When the fastener 256 is rotatedcounterclockwise, it may be threaded in one direction deeper into thethreaded bore 220 of the stem component 218 and in the oppositedirection deeper into the mounting post 22 of the component 136. As aresult, the fastener 256 is rotated in only a single direction toassemble the component 236 with the stem component 218.

As shown in FIGS. 12-13, when the fastener 256 is rotated clockwise, itmay be drawn in one direction, out of the threaded bore 220, and it maybe drawn in the other direction, out of the mounting post 22 of thecomponent 135. In that way, the fastener 256 is rotated in only a singledirection to dissemble the component 236 from the stem component 218. Aswith the fastener 56, the shaft 292 of the fastener 256 includes a toolsocket 106 that is shaped to accept a surgical instrument tool 150. Thesurgical instrument 150 may be used to assemble and dissemble tocomponents 136, 218.

In the illustrative embodiment, the thread pitch and lead of the section290 matches the thread pitch and lead of the section 294 so that onerotation of the fastener 256 in either direction results in the sametravel axially for the sections 290, 294. Further, the section 290 has adiameter 302 that is greater than a diameter 82 of the first passageway70 of the tibial tray component 14 (or femoral component 12).Accordingly, the section 290 of the fastener 256 may positioned in thesecond passageway 72 of the tibial tray component 14 but does not passbeyond the rim surface 74 into the first passageway 70.

While the disclosure has been illustrated and described in detail in thedrawings and foregoing description, such an illustration and descriptionis to be considered as exemplary and not restrictive in character, itbeing understood that only illustrative embodiments have been shown anddescribed and that all changes and modifications that come within thespirit of the disclosure are desired to be protected.

There are a plurality of advantages of the present disclosure arisingfrom the various features of the method, apparatus, and system describedherein. It will be noted that alternative embodiments of the method,apparatus, and system of the present disclosure may not include all ofthe features described yet still benefit from at least some of theadvantages of such features. Those of ordinary skill in the art mayreadily devise their own implementations of the method, apparatus, andsystem that incorporate one or more of the features of the presentinvention and fall within the spirit and scope of the present disclosureas defined by the appended claims.

The invention claimed is:
 1. A method for joint line assembly of anorthopaedic modular knee prosthesis assembly, the method comprising:aligning a first prosthetic component with a second prostheticcomponent, wherein the first prosthetic component includes (i) a firstend, (ii) a second end opposite the first end, (iii) an elongated bodyextending from the first end to the second end, and (iv) a threaded boredefined in the first end, wherein the second prosthetic componentincludes (i) a bone-engaging surface, (ii) a first opening, and (iii) amounting post extending from the bone-engaging surface along alongitudinal axis, the mounting post including a second opening definedin a free end and an inner wall that extends inwardly from the secondopening to the first opening to define a first passageway that extendsfrom the first opening and a second passageway in the mounting post thatextends from the second opening, and wherein (a) the inner wall of themounting post includes a rim surface at an intersection of the firstpassageway and the second passageway, (b) the first passageway extendsbetween the first opening and the rim surface and the second passagewayextends between the rim surface and the second opening, (c) the innerwall includes a plurality of internal threads in the second passageway,and (d) the second passageway has a diameter larger than a diameter ofthe first passageway, aligning a fastener with the first prostheticcomponent and the second prosthetic component, the fastener having anelongated shaft including (i) a first axial section having a firstplurality of threads sized to engage with the threaded bore of the firstprosthetic component, and (ii) a second axial section positionedopposite the first axial section, the second axial section having asecond plurality of threads sized to engage with the plurality ofinternal threads of the second prosthetic component, rotating thefastener in a first direction to simultaneously thread the first axialsection and the second axial section into the threaded bore defined inthe first end of the first prosthetic component and the secondpassageway in the mounting post of the second prosthetic component,respectively, so as to assemble the first prosthetic component with thesecond prosthetic component, wherein the second axial section of thefastener has a diameter larger than the diameter of the firstpassageway, such that the first passageway is sized to prevent thesecond axial section of the fastener from passing beyond the rim surfaceand into the first passageway when the second axial section of thefastener is threaded into the second passageway, and wherein the firstprosthetic component is an elongated stem component.
 2. The method ofclaim 1, further comprising: advancing a tool through the firstpassageway defined in the second prosthetic component, engaging an endof the tool with the second axial section of the fastener, and rotatingthe tool in a second direction to simultaneously move the first axialsection and the second axial section out of engagement with the firstprosthetic component and the second prosthetic component, respectively.3. The method of claim 1, wherein the first axial section has a samediameter as a diameter of the second axial section.
 4. The method ofclaim 1, further comprising: advancing a tool through the firstpassageway defined in the second prosthetic component, and engaging anend of the tool with the second axial section of the fastener, whereinrotating the fastener in a first direction to simultaneously move thefirst axial section and the second axial section into the firstprosthetic component and the second prosthetic component, respectively,includes rotating the tool in the first direction.
 5. The method ofclaim 1, further comprising rotating the fastener in a second directionto simultaneously move the first axial section and the second axialsection out of engagement with the first prosthetic component and thesecond prosthetic component, respectively.
 6. The method of claim 1,wherein the first plurality of threads comprises a first thread pitchand the second plurality of threads comprises a second thread pitch thatmatches the first thread pitch.
 7. The method of claim 1, wherein thesecond prosthetic component is a femoral prosthetic component.